This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-304575, filed Sep. 28, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to electronic cards formed of a double-sided printed circuit board.
2. Description of the Related Art
Electronic cards, such as an SD (Secure Digital) card which is formed of a non-volatile semiconductor memory device and which constitutes, for example, a small-sized memory card is inserted into and removed from an electronic equipment by gripping it. Thus, measures must be taken to prevent static electricity from being generated.
Small-sized memory cards like the above, must be thin. In order to realize a very thin card, therefore, card surfaces may be formed by covering only a component mounted surface formed on one surface of a printed circuit board, with a card case, and coating a wiring pattern portion on the other surface with a protective film composed of, for example, ultraviolet hardened resin. More effective electrostatic prevention measures are required for such small-sized very thin electronic cards.
Further, to aid the manufacture of electronic cards, electrolytic plating patterns required for gold plating or the like in a desired circuit pattern are continuously disposed over a plurality of circuit boards before the individual circuit boards are blanked. After the individual circuit boards have been obtained, the patterns remain at the edges of the circuit boards. These electrolytic plating patterns remain connected to circuit patterns forming internal signal paths. Thus, when a discharge current induced by static electricity flows into the patterns formed at the edges of the circuit board, it may destroy the internal circuit or data or result in other problems. Thus, effective electrostatic measures have been required particularly for the patterns formed at that edge of the circuit board which is located closer to the grip portion.
As described above, more effective electrostatic prevention measures are conventionally required for electronic cards such as a small-sized memory card. In particular, effective electrostatic measures are conventionally required for the patterns formed at that edge of the circuit board which is located closer to the gripped portion.
An embodiment of the present invention is directed to an electronic card that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
According to an embodiment of the present invention, an electronic card comprises:
a printed circuit board which has components mounted on one surface thereof;
a cover member which covers the one surface of the printed circuit board;
external connection terminals provided on the other surface of the printed circuit board;
charge prevention circuit patters provided on the other surface of the printed circuit board; and
a film which coats the other surface of the printed circuit board except for the external connection terminals.
Additional objects and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention.
The objects and advantages of the present invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.